On Fri, Oct 6, 2017 at 8:33 AM, Richard Biener <rguent...@suse.de> wrote:
> On Fri, 6 Oct 2017, Sebastian Pop wrote:
>
> > On Fri, Oct 6, 2017 at 6:56 AM, Richard Biener <rguent...@suse.de>
> wrote:
> >
> > >
> > > The following fences off a few more SCEVs through scev_analyzable_p
> given
> > > at the end we need those pass chrec_apply when getting a rename through
> > > SCEV.
> > >
> > > The SCEV in question is
> > >
> > > {(integer(kind=4)) {0, +, {1, +, 1}_1}_1, + 1}_2
> > >
> > > which fails to chrec_apply in the CHREC_LEFT part because that part
> > > is not affine (and we're usually not replacing a IV with a constant
> > > where chrec_apply might handle one or the other case).
> > >
> > > Bootstrapped and tested on x86_64-unknown-linux-gnu.
> > >
> > > This fixes three out of the remaining 8 codegen errors in SPEC CPU
> 2006.
> > >
> > > Ok?
> > >
> > > Thanks,
> > > Richard.
> > >
> > > 2017-10-06 Richard Biener <rguent...@suse.de>
> > >
> > > PR tree-optimization/82449
> > > * sese.c (can_chrec_apply): New function.
> > > (scev_analyzable_p): Check we can call chrec_apply on the SCEV.
> > >
> > > * gfortran.dg/graphite/pr82449.f: New testcase.
>
> >
> > > Index: gcc/sese.c
> > > ===================================================================
> > > --- gcc/sese.c (revision 253477)
> > > +++ gcc/sese.c (working copy)
> > > @@ -421,6 +421,27 @@ invariant_in_sese_p_rec (tree t, const s
> > > return true;
> > > }
> > >
> > > +/* Check whether we can call chrec_apply on CHREC with arbitrary X and
> > > VAR. */
>
> > +
> > > +static bool
> > > +can_chrec_apply (tree chrec)
>
Could we use scev_is_linear_expression ?
It seems like can_chrec_apply has the same semantics.
> > > +{
> > > + if (automatically_generated_chrec_p (chrec))
> > > + return false;
> > > + switch (TREE_CODE (chrec))
> > > + {
> > > + case POLYNOMIAL_CHREC:
> > > + if (evolution_function_is_affine_p (chrec))
> > > + return (can_chrec_apply (CHREC_LEFT (chrec))
> > > + && can_chrec_apply (CHREC_RIGHT (chrec)));
> > > + return false;
> > > + CASE_CONVERT:
> > > + return can_chrec_apply (TREE_OPERAND (chrec, 0));
> > > + default:;
> > > + return tree_does_not_contain_chrecs (chrec);
> > > + }
> > > +}
> > > +
> > > /* Return true when DEF can be analyzed in REGION by the scalar
> > > evolution analyzer. */
> > >
> > > @@ -449,6 +470,7 @@ scev_analyzable_p (tree def, sese_l ®
> > > || !defined_in_sese_p (scev, region))
> > > && (tree_does_not_contain_chrecs (scev)
> > > || evolution_function_is_affine_p (scev))
> > >
> >
> > Why isn't evolution_function_is_affine_p returning false on {0, +, {1, +,
> > 1}_1}_1?
> > This is quadratic.
>
> It returns false on that but the CHREC we ask it on is
>
> {(integer(kind=4)) {0, +, {1, +, 1}_1}_1, + 1}_2
>
> only the initial value is "quadratic".
>
Right.
If I understand correctly, the scop is the body of loop_1,
and we do not need to represent the quadratic evolution
of the initial value.
